Re: [Emc-users] EDM machining, user interface

[ceenbot]

Hi Nicklas,

I have a large Makino wire EDM with a working envelope of 1200x900x300mm with 
UV axes for tapered cutting.  I also am looking to update the machine but have 
other projects in front of it.  One neat feature of my wire machine is edge 
finding and locating the center of a hole if re-positioning material.  
Realigning the coordinate system based on a new position or rotation of the 
material would be nice by locating the center of a pair of holes.  My Makino 
supports some of this already but it is a 1980 reel to reel mag tape machine 
and the controller is not too practical today.

Is yours a ram or wire machine?  If wire, have you worked out movement history 
to back a wire out of the material?


Dennis


>  From: Nicklas Karlsson 
>  
>  Yes I am retrofitting an old EDM machine. It have been a year two before I
>  started but finally I have  all the needed hardware. As is now I am
>  starting to think about user interface and could vaguley remember somebody
>  talked about it earlier, worst problem is probably I am not totally sure
>  what is exactly needed and then it come to motions basically have very
>  little knowledge what moves might be useful.

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Re: [Emc-users] Aluminum sources

[ceenbot]

For cost comparison purposes we have custom dies made in China for $900 and 
anodized aluminum is about 2x the market price of bulk aluminum.  Our 
extrusions were anywhere from 2" - 7" wide and we generally had a pallet or two 
made at a time.  


Dennis


>  ---Original Message---
>  From: Erik Friesen 
>  To: Enhanced Machine Controller (EMC) 
>  Subject: [Emc-users] Aluminum sources
>  Sent: Apr 12 '16 20:36
>  
>  Any ideas where to find anodized profiles and aluminum sheet like this?
>  
>  https://www.frontpanelexpress.com/products/enclosures/
>  
>  We have sent quite a bit of money their way, would like to do this in house.

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Re: [Emc-users] Linuxcnc on arm

[ceenbot]

There isn't a need to exchange parts once they are in place.  Board 
manufacturers get by with flash gold plated connectors because they are lower 
cost and the flash plating is only good for so many swipes before the connector 
cannot meet its original spec of contact resistance, current capacity, etc.  
The spec for PCI connector plating Finish 4 is a mere 2 mating cycles.  If 
subject to any vibration like my pneumatic ATC exhibits on the machine it 
wiggles the contact surfaces just a little and chafes a bit more.  My pick and 
place accelerates its carriage to maybe 1-2m/s with Sanmotion drives and 
servos.  You can feel vibration & movement on the frame of the machine no 
matter how the 1600# machine is anchored down.

My Bridgeport probably started having connector issues after 20 years of use.  
Now maybe once a month I get a servo amp fault or other random issue related to 
the card cage.  I remove the cards and clean PCB fingers with alcohol then 
insert the cards a number of times to get into fresh metal.  This works again 
for a while.  I just need something I can count on without the machine 
faulting.  Then I would make more parts.


Dennis


On Wed, 23 Mar 2016 15:11
 wrote:

>  
>  Do you have to exchange your SATA and PCIe devices very often? I only do
>  with my test systems. The controllers for machines might get a SATA or
>  PCIe device swapped once in it's lifetime of several years.

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Re: [Emc-users] Linuxcnc on arm

[ceenbot]

I second the point about not using a PC.  Most of the CNC reliability issues I 
see are with backplane card edge connectors for DC servo drives and connectors 
subject to vibration/chafing of gold plating and oxidation of tin plating.  A 
consumer grade PC motherboard is not meant for machine vibration.  USB 
keyboard, PCI slot and SATA connectors seem to be a weak point as their 
insertion lifetimes are on the order of 50 or so.  I would prefer a 1 or 2 PCB 
solution with tightly coupled interconnects (possibly soldered) board to board 
just to eliminate potential sources of connector failure.  

My still functional 29 year old Bridgeport Interact 412 uses a Heidenhain 151 
CNC controller.  It's 12MHz TMS9995 microprocessor is surrounded with TTL 
counters for encoder position and associated logic that generates 0-10V spindle 
and brush DC servo command data.  Any single core 1GHz A9 would run circles 
around what I have now. The cost of a PC versus a purpose-built embedded CNC 
controller is not an issue for me as long as the controller does not creep into 
the thousands of $$.  Machine reliability and up time come first but safety is 
right up there as well.  You can imagine what servo runaway is like when an 
encoder cable is broken.  In my case mouse chewed.  

I've been following the BBB discussions and think the BBB would work for the 
networking & GUI and any RT servo timing should be handled by a FPGA.  The 
BBB's 200MHz PRUs are OK for a simple 3D machine but my 6 head pick and place 
has X & Y axes, (12) Nema 11 stepper motors and 112 pneumatic feeders.  A 
little beyond a BBB's I/O count.

We developed a FPGA based stepper algorithm using the popular DRV8825 Reprap 
microstepping driver.  The 8825 phase current is dynamically varied based on 
RPM and these tables are stored in the FPGA.  Changing phase current vs. RPM 
allows us to tune around motor and carriage resonance points.  We took a Nema 
17 stepper and had it spinning at 3000RPM with 40-bit speed resolution.  At 
full speed the 32x microstepping clock was 320kHz.  Probably something a PRU 
could do in assembly language but is more flexible with VHDL.  

I'm considering the BBB and a Spartan-6 cape for ~$100 and the Zynq-based 
Snickerdoodle for $62-$157.  The TS-4900 also looks appealing.


Dennis


On Wed, Mar 23, 2016 at 6:27 AM, Erik Friesen <
e...@aercon.net> wrote:
>  
>  I don't want bang for my buck.  What I want is a control board I can drop
>  into my haas, and doing it with x86 isn't very feasible.  Dropping a
>  embeddedarm ts4900 on a custom baseboard would be real slick, and it seems
>  that it could surely compete with the 1990's era motorola running at 40mhz.

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Re: [Emc-users] Capeless BBB

[ceenbot]

Hi Andy,

I created a DDS algorithm for our stepper-based robots that would use digital 
step rates of 1pps up to 300pps.  This was the max speed using the battery, 
Freescale driver and steppers we had.

The DDS interrupt algorithm ran on an Atmel 20MHz mega part with 1Hz 
resolution.  It allowed us to set one stepper motor to 129Hz and the other to 
130Hz step rates for example and they would stay in lock at these ratios.  The 
interrupt was driven from a crystal controlled timer so the timing was pretty 
stable.  I could have expanded the resolution of the DDS to 0.1Hz or 0.01Hz but 
we did not need any better resolution for our application than 1Hz.  A stepgen 
routine running from a 1GHz processor should be capable of decent stepper 
timing resolution.

I would set up a hardware timer interrupt and place about 30 instructions of 
fluff in the interrupt.  Set an I/O pin low at the start of the interrupt and 
high at the end of the timer interrupt.  This way you can scope the amount of 
time spent in the interrupt versus the rest of the code/OS.  Increase the 
frequency of the timer interrupt until you are spending 20-30% of CPU time in 
the interrupt versus other code.  This will tell you how many timer 
interrupts/second the CPU can run without corrupting the stack and messing with 
operation of the OS.

A 1GHz part should run timer interrupts at 5-20MHz or so depending on the 
efficiency of stack entry & exit.  At 10MHz you could control a number of 
steppers up to speeds of 1000.000Hz with a granularity of 0.001Hz.  That has a 
nice CNC capability to it.

One stepper could be running as fast as 1000.000Hz on one axis and another 
could run at as low 0.001Hz, tracking the first motor.  For every 1M steps of 
the first stepper the second would step once.  

So I think the BBB is very capable.  What kind of power drivers are you 
planning to use: step/dir or something else?  We drove the bipolar steppers 
directly with Freescale MC33926 drivers using the micro's I/O pins.


Dennis

>  ---Original Message---
>  From: andy pugh 
>  To: Enhanced Machine Controller (EMC) 
>  Subject: [Emc-users] Capeless BBB
>  Sent: Aug 16 '13 04:39
>  
>  Is it possible to use a BBB as a step generator or encoder reader
>  without any sort of cape at all?
>  
>  The application is synching a stepper motor to an encoder with a
>  variable ratio.
>  
>  --
>  atp
>  If you can't fix it, you don't own it.
>  http://www.ifixit.com/Manifesto

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Re: [Emc-users] solder paste

[ceenbot]

Hi Dave,

That's funny.  I am an engineer but opinions and others' expertise are always 
welcome.  That is how I learn.  I found some inexpensive HPLC pumps on ebay but 
most are sold as-is.  You don't know if the seals are any good and if some 
yahoo like me tried to push solder paste through it...well who knows what shape 
the pump is in.  

I do have a larger pump I purchased from the 3M surplus store in St. Paul, MN.  
The pump is a screw piston type and is rated to somewhere near 30,000 PSI.  The 
assembly had a bunch of high pressure proportional valves and stainless tubing. 
 The pump cylinder is probably 5 cubic inches.  Quite large for a solder paste 
dispenser.

I have not looked into HP's paint heads.  Sounds interesting because one would 
think the paint media is a bit thicker than ink.  The older inkjet heads won't 
work because the ones I'm familiar with heat up a small thin film resistor to 
boil a spec of ink and this heated ink blows through a small orifice to the 
paper.  If I boiled solder paste I would have boiled solder paste.

Eventually I will find something that will work.  This is the idea kicking 
phase at the moment.


Dennis


>  Dennis:
>  I think that is a question for an engineer.
>  I just used an HPLC for analysis of low levels of Vit A in animal
>  feeds.
>  There are really no wrong questions ... how else does on learn?
>  Questions are much cheaper than an expensive HPLC pump.
>  
>  If you can take a look as some of the newer colored (paint/dye) heads in
>  HP printers. Cute technology IIRC.
>  
>  Dave

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Re: [Emc-users] solder paste

[ceenbot]

Thanks Dave.  Thought I would throw it out there.  I don't have any experience 
with a HPLC pump.  What if the geometry were larger and the check valves could 
cope with a suspended solid?  Think on the scale of a small hydraulic valve 
body.


Dennis


>  HPLC pumps are made to deliver precise flows of organic (pretty much)
>  liquids. Even suspended particulates are going to mess with the valving.
>  Classically, the mobile phase should pass thru a millipore filter;
>  probably .3 um. Sorry to be a wet blanket.
>  
>  Dave

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Re: [Emc-users] solder paste

[ceenbot]

I found a high pressure pump (up to 40,000PSI) that may work with solder paste. 
 These are readily available on ebay as high pressure liquid chromatography 
(HPLC) pumps.  A description is here:  
http://www.lcresources.com/resources/getstart/2b01.htm

Even if a standard Waters style pump has geometry too small for solder paste it 
would not be too difficult to make a slightly larger pump with check valves 
specifically designed for solder paste.  OTOH it is a $100-$200 experiment to 
see if a Waters pump would work because they typically use a sapphire piston 
and sapphire check valve balls for high pressure & precise metering.

Kind of a neat design.


Dennis

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Re: [Emc-users] CNC Grinder

[ceenbot]

Andy,

Do you know if the Accupin method is still patent protected?  Within the last 
year I looked up the ball-in-tube patent and those guys are pretty proud of 
their round balls.  To me, pins are just as viable.  Thanks for the "Accupin" 
reference.


Dennis


>  
>  I think that a multi-pole one would work. Such a device would not be
>  far in principle from the "Accupin" scales on Skunkwork's K&T or the
>  ball-in-tube scales.
>  
>  --
>  atp

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Re: [Emc-users] solder paste

[ceenbot]

Hi Ralph,

Wow.  I had not thought of using thin FR4 and milling it out for a stencil.  I 
do have some fairly thin PCB material used for multilayer stackup.  I'll have 
to investigate cutting my own.  That may save some time if properly automated.  
My only accurate machine is my Bridgeport CNC and it only had a 6000 RPM head 
unless I drop in a BT40 speed head.  Always wanted one of those.  Milling with 
a 0.010" bit at 6000 RPM would be slower than watching grass grow.  What is 
your LPKF RPM and feed rate?


Dennis


>  ---Original Message---
>  From: Ralph Stirling 
>  To: gro...@homanndesigns.com , Enhanced Machine 
> Controller (EMC) 
>  Subject: Re: [Emc-users] solder paste
>  Sent: Aug 07 '12 11:35
>  
>  We cut our own stencils with a 0.010" end mill on our LPKF pcb milling 
> machine.
>  For material we use 0.005" thick FR4 laminate without copper, purchased in 
> big
>  sheets (2'x2' or so) from Insulectro (if I recall correctly).  I use the 
> same paste
>  in a syringe that we use for the occasional manual dispensing for 
> stenciling.  I
>  just take the needle off and dispense a bead across the width of the 
> stencil.  I
>  made a simple frame for holding the pcb and the stencil and use a putty knife
>  to spread the paste.  We do this for complex one-off boards as well as any
>  boards we make in multiples.
>  
>  -- Ralph

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Re: [Emc-users] solder paste

[ceenbot]

Hi Peter,

I agree with the auger-type metering as opposed to relying on the temperature 
dependent viscosity of paste.  I'm dwelling on an idea to put a small hole in a 
stainless stencil strip and filling the hole under pressure.  The small stencil 
strip would move from "fill under pressure position" to eject position as it 
slid from side to side.  When the hole is filled it would have a deterministic 
volume.  

Eject position would position the paste dot under an air steam for a brief 
stink, not staying in position under the air but just long enough to be 
ejected.  The little burst of air would push the dot through a relatively short 
needle to minimize drag.  The guide would be just long enough for aiming 
purposes.  How accurate were you in school with spitwads and a straw?

One issue I see is entraining air into the solder paste when the empty carrier 
is returned to fill position and the paste displaces the void.


Dennis


>  ---Original Message---
>  From: Peter Homann 
>  To: Enhanced Machine Controller (EMC) 
>  Subject: Re: [Emc-users] solder paste
>  Sent: Aug 07 '12 07:23
>  
>  Hi Gene,
>  
>  It costs me about $80 for a laser cut stencil. The process of applying the
>  paste is shown here.
>  
>  
> http://www.homanndesigns.com/index.php?option=com_content&view=article&id=54:manual-process-for-applying-solder-paste-via-a-stencil&catid=35:smt&Itemid=55
>  
>  It takes less than 90 seconds to apply paste to a panel with this method.
>  
>  I also have a pneumatic paste dispenser that I use for prototypes and also 
> for
>  reworking. The paste in the syringes is a lot less viscous so it can be
>  dispensed through the needle. It is not suitable for use with a stencil as 
> the
>  stencil paste is not suitable for use in a syringe.
>  
>  I did have a plan to make a paste dispenser machine as I have an auger driven
>  paste dispenser heat of an old Camalot machine, along with some nice rails 
> for
>  the X/Y axis. But in the end, the stencil works so well. If I was doing a lot
>  of one-off, it may be a different story. One day I'll make it just to see how
>  well it works.
>  
>  For an automated dispensing machine an auger dispenser is essential as the
>  viscosity of the paste changes with temperature. After about 50 dots from a
>  pneumatic syringe dispenser, the syringe is noticeably warm, thinning out the
>  paste. When using the pneumatic syringe dispenser, I'm continuously adjusting
>  the dispense shot time to keep the dot the size I want.
>  
>  Cheers,
>  
>  Peter
>  
>  On 7/08/2012 4:51 PM, Gene Heskett wrote:
>  > On Tuesday 07 August 2012 02:32:47 cogoman did opine:
>  >
>  >> On 08/06/2012 09:49 PM, Jon Elson wrote:
>  >>> I make my own stencils for these.  It is kind of a pain, but I'm
>  >>> CHEAP!
>  >>
>  >> How about the cheapest CNC to build, an XY plotter like this:
>  >>
>  >> https://www.youtube.com/watch?v=WyLPpGdfR7s
>  >
>  > That seems to be pretty sloppy, with pen tilt being a major problem.  In
>  > addition to that, a 3rd tension pulling down would reduce the positioning
>  > errors from the sag in the upper support lines.  Ok for crayon on the wall
>  > art, but obviously very slow.
>  >
>  >> but with the laser from an old DVD burner for the pen.  You could
>  >> produce plotter output files and convert them to G-code, and then cut
>  >> them out of thin plastic (just shield your eyes while it runs, or box it
>  >> in.
>  >
>  > Could one use the resultant laser cut stencil as if it was a silk screen to
>  > apply the solder paste?
>  >
>  > If so, that would certainly cut large hunks of time out of the process once
>  > the stencil was made.  However, having the paste exposed to the air while
>  > on the stencil would make me want to figure out a way to flood the area
>  > with GN2 to slow the oxidation that would occur while doing the time
>  > consuming pick-n-place, and on to the reflow oven.  All of that should be
>  > in an oxygen free atmosphere to preserve the solder ability.  Quality wise
>  > there probably would be a better flooding gas than GN2, but GN2 is
>  > relatively cheap.
>  >
>  >
>  >> Getting the tool set in line would take some time, but once you get
>  >> the hang of it, it would save time in the long run.
>  >>
>  >
>  >
>  > Cheers, Gene
>  >
>  
>  --
>  -
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>  
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Re: [Emc-users] solder paste

[ceenbot]

I have tried laser cut plastic stencils but they are not a joy to use.  The 
raised cut edges are about 20% higher than the plastic material itself and the 
squeegee and paste get caught up on them.  It leaves a thin layer of paste on 
top of the plastic between the cutouts.  Using a $80 stainless stencil is like 
liquid gold compared to plastic.  Part of the issue is the ability to remain 
flat against the PC board as the squeegee is pulled across.  Solder paste will 
build up in any voids under the stencil if the bottom of the stencil is not 
absolutely flat against the PC board.  When you are dealing with stencils in 
the 0.005" - 0.010" thick range, having a 0.005" gap between the stencil and 
board results in islands of paste.  If I get a bad stenciling I scrape the 
board with a razor blade and start again.

IMO using a syringe by hand is better than a plastic stencil for prototypes.  
This is why I'm looking at automating this process.  

I really don't have an issue with solder paste drying out.  Batches of 
stenciled boards have been exposed to air for as long as 5 hours before they 
hit the oven.  That's pushing the limit a little as a small number of resistors 
will tombstone because the solder paste is not sticky enough to hold down both 
sides of the resistor when reflowing.  Three hours is still very workable.  
Some parts like JST SMT vertical connectors cannot be picked by a vacuum so 
they have to be placed by hand after the P&P.  I'm also one 8mm feeder short of 
what I need for this board so some other parts need to be placed by hand.  The 
P&P is not perfect either.  It has about a 99% placement rate which I think is 
pretty good.  This means a resistor may have rotated a bit when slammed into 
the solder paste and no longer contacts both pads on the board.  There is a 
visual verification and manual "correction" process done for each board.  The 
majority of boards I run are double sided so all SMT processes are performed 
twice.  This is one of the reasons I would like a paste printer because the 
manual stencil printer requires a lot of adjusting and fixturing changes when I 
go from side 1 (flat, no parts) to side 2 with lumpy parts on the back side.  
It would be better if I actually made fixtures for each type of board but where 
does the time go.  

A paste printer with adjustable width rails on a conveyor would lock a board in 
place even if the board had parts mounted on the bottom side.  I envision a 
stepper driven back gauge to set the panel width to 125mm, etc. depending on 
the board.  The back gauge would have a little bit of spring tension for board 
size variations (fixed position front guide).

I made fixtures to run very small boards through the P&P (postage stamp sized 
if individually routed).  It is a spring loaded fixture that keeps the PC board 
height the same as if there were no fixture.  I also have adjustable aluminum 
extrusion fixtures to gently suspend the boards as they go through the oven for 
the 2nd side of the board.  The oven conveyor would damage the bottom side 
parts if the board were sitting directly on the oven conveyor itself.  The 
boards are still at melt temperature when pulled off the conveyor for about 3 
seconds and subject to bumping, etc.  An outbound conveyor board stacker/cooler 
is also on the drawing board.


Dennis



>  ---Original Message---
>  From: cogoman 
>  To: Enhanced Machine Controller (EMC) 
>  Subject: Re: [Emc-users] solder paste
>  Sent: Aug 07 '12 00:11
>  
>  On 08/06/2012 09:49 PM, Jon Elson wrote:
>  > I make my own stencils for these.  It is kind of a pain, but I'm CHEAP!
>  How about the cheapest CNC to build, an XY plotter like this:
>  
>  https://www.youtube.com/watch?v=WyLPpGdfR7s
>  
>  but with the laser from an old DVD burner for the pen.  You could
>  produce plotter output files and convert them to G-code, and then cut
>  them out of thin plastic (just shield your eyes while it runs, or box it in.
>  
>     Getting the tool set in line would take some time, but once you get
>  the hang of it, it would save time in the long run.

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Re: [Emc-users] solder paste

[ceenbot]

Hi Jon,

I use a manual stencil printer now and it does work pretty well.  The issue is 
banging out a stencil for all of the proto boards I make.  There are about 30 
proto designs created per year and since the boards change a bit before they 
become final, so does the stencil.  I don't see the Mydata printer being used 
for high volume in large production houses  as much as high flexibility (in 
setup) in a lower to medium sized assy house.

The vision is to spend 1-2 hours programming a printer then let it loose on the 
boards.  A typical board run for me is 200 pcs.  I agree with printer 
maintenance.  Mark recommended a peristaltic pump.  I do like those.  A short 
piece of small high quality tubing is easily disposed of.  Mark also provided 
this link as an alternative method to the jet head: 
http://www.nordson.com/en-us/divisions/asymtek/Documents/Articles/2008_07_SMT_advanced_solder%20paste_NordsonASYMTEK.pdf

I also have a 2000# automatic stencil printer that will accept up to 27" x 27" 
framed stencils.  It was part of a package deal and I did not say no.  The 
smallest framed stencil it will handle is maybe 20" x 20".  The boards/panels 
can be smaller of course.  My P&P conveyor is only 12" wide.


Dennis



>  ---Original Message---
>  From: Jon Elson 
>  To: ceen...@in-front.com, Enhanced Machine Controller (EMC) 
> 
>  Subject: solder paste
>  Sent: Aug 06 '12 11:32
>  
>  ceen...@in-front.com wrote:
>  > Mydata has a MY500 solder paste printer but it about $200k USD more than I 
> want to spend in the next year or so on a printer.  It looks to be a nice 
> machine.  I may see if I can get a replacement head for a MY500 if I can.
>  >  
>  Printing solder paste with a stencil is amazingly low-tech.  The only
>  thing hard to make is the stencil.
>  You can buy these, but for many short-run projects the cost would add
>  up.  I have a way to make
>  stencils myself from .003" brass shim stock material, it is done just
>  like making a PC board.
>  You can probably do this with a laser printer and heat transfer the
>  toner/resist.
>  
>  I think keeping a paste jet printer working would put you in the mad
>  house.  Ink jet
>  printers generally don't work if left sitting for a few days, I'd expect
>  it to be
>  WAY worse with solder paste in there!
>  
>  Jon
>  

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Re: [Emc-users] OT - Ford diesels

[ceenbot]

Hi Andy,

What types of diesel injectors are you working with?  Direct injection?  I'm a 
fan diesel direct injection.  There are potential uses for piezoelectric 
injectors other than just pushing oil.  I am looking for a similar injector to 
deposit solder paste onto circuit boards.  

Mydata has a MY500 solder paste printer but it about $200k USD more than I want 
to spend in the next year or so on a printer.  It looks to be a nice machine.  
I may see if I can get a replacement head for a MY500 if I can.

At the 37 second mark they show a cutaway of the Mydata My500 solder paste 
print head:
http://www.youtube.com/watch?v=cC41j-LJZm4

My thought was to get a fairly low volume diesel direct injector (i.e. 1L to 2L 
4-cyl diesel car) and grind away the lower section of the nozzle which has the 
6 or 8 pinholes to allow solder paste to exit a bit more freely.  I don't want 
a spray pattern but just a micro dot deposited below the injector.  I think the 
velocity and volume can be altered a bit by changing the wave shape applied to 
the injector.  I also don't need 30k PSI as this may make the paste do weird 
things like go through the PC board.  From what I've read the piezo stack takes 
about 100V to fire but piezo ceramics are static in nature so applying a DC 
potential of 100V will hold the stack at its extended position and shorting it 
to ground will constrict the stack.

In the US Ford etc. diesel trucks are plentiful but I don't feel like spending 
$600 on a truck sized injector + a core charge.  So, if anyone has a new/used 
injector lying around they don't have plans for I may be interested in 
experimenting with one.  It should be a direct injector but please correct me 
if a mechanical injector would work as well.  Some tuning shops match injector 
flow rates but I'm not sure what happens to the ones with plugged pinholes or 
with flow rates just lower than needed.  For an experiment it would not matter 
to me.  You may say I'm all wet thinking about direct injection for a solder 
paste printer and that would be ok.


Thanks,
Dennis


>  ---Original Message---
>  From: andy pugh 
>  To: dengv...@charter.net, Enhanced Machine Controller (EMC) 
> 
>  Subject: Re: [Emc-users] OT - Ford diesels
>  Sent: Aug 04 '12 12:24
>  
>  The same things have made Diesels a lot faster. 100hp / litre is
>  pretty common in production engines. I remember when that was a race
>  motorcycle tune.
>  The engine I am working on is the low-power version of the 2.0 at
>  180hp and 420Nm (320 ft.lb)
>  
>  --
>  atp

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Re: [Emc-users] Rotate Workpiece Coordinate System?

[ceenbot]

I'm interested in camera recognition of fiducial marks on printed circuit 
boards as well as an upward looking camera to determine orientation of SMT 
components when picked with a vacuum head.  This can be applied to stencil 
printers, solder paste printers, SMT pick-and-places, etc.

The SMT pick-and-place I have is made pretty well except the implementation 
could have been better.  The XY servos are brushless DC Sanmotion drives by 
Sanyo and there are 12 steppers and stepper drivers on the main pick-and-place 
head.  When the carriage whips around it puts stress on the cabling between the 
stepper drivers and steppers.  The manufacturer used hot melt glue as a strain 
relief for the cable wires.  Doesn't work too well.  I have had to repair wire 
crimps a number of times.  The manufacturer also did not have a proper pin 
crimper - looks like they used a pliers.  Aside from some implementation issues 
like this it isn't too bad of a machine.  If I had the time I would rewrite the 
application as it could use some refining.  The biggest thing stopping me is 
the fire wire cameras and recognition routines.  It's rated at 14,000 
components/hour but I run it slower to keep it reliable.


Dennis



>  ---Original Message---
>  From: Ralph Stirling 
>  To: Enhanced Machine Controller (EMC) 
>  Subject: Re: [Emc-users] Rotate Workpiece Coordinate System?
>  Sent: Jul 03 '12 17:10
>  
>  I had some success with using a USB microscope and the python
>  opencv libraries.  I was looking for the center of a circle of specific
>  diameter and calculated the distance from this found center to
>  the desired position, then moved by that distance to home the axis.
>  It was a fairly quick-and-dirty test I did, but I was quite encouraged
>  by the results.
>  
>  -- Ralph

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Re: [Emc-users] SCARA robot arm 3D printer

[ceenbot]

This link is for a reprap SCARA: http://www.youtube.com/watch?v=Cquw7dvR80A

There was a conversation a while back about how many plastic Yoda heads and 
other fast prototyped plastic waste would end up in land fills.  I see the 
above reprap SCARA being a positive and constructive engineering use for a 
reprap machine.  The HF06 used stepper motor and linear bearings but the rest 
is pretty much made with a reprap.

Cool stuff.


Dennis


>  ---Original Message---
>  From: Jeshua Lacock 
>  To: Enhanced Machine Controller (EMC) 
>  Subject: Re: [Emc-users] SCARA robot arm 3D printer
>  Sent: Jun 20 '12 02:25
>  
>  
>  On Jun 19, 2012, at 9:46 AM, andy pugh wrote:
>  
>  > On 19 June 2012 15:46,   wrote:
>  >
>  >> As the printer is a SCARA arm
>  >
>  > This is an interesting development, as it has more printable
>  > components than a conventional RepRap. You could (in theory) print the
>  > arms, whereas printing linear slides is more tricky.
>  
>  Wow, that is a really great idea! Pretty much the only thing you couldn't 
> print is the steppers (and electrical components) - but those things are 
> cheap!
>  
>  
>  Cheers,
>  
>  Jeshua Lacock
>  Founder/Engineer
>  3DTOPO Incorporated
>  
>  Phone: 208.462.4171
>  

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Re: [Emc-users] CO2 Laser Control

[ceenbot]

Hi Jeshua,

I spent a number of years feeding a Trumpf 4kW industrial laser.  It has been a 
while but I'll dump what I know.

1.  The output of the laser beam changes width as it exits the laser tube.  The 
industrial machines use a patented fixed length beam delivery system.  Think of 
this as a trombone arrangement with 2 90 degree mirrors mounted in the slider.  
As the carriage moves from left to right and front to back, the trombone slider 
moves in and out to keep the lens at the same distance from the laser tube 
throughout the travels of the machine.  The beam waist (beam diameter) does not 
necessarily disperse to infinity like a solid state laser pointer.  A CO2 will 
have nodes and anti-nodes where the waist diameter gets slightly larger and 
smaller as you move away from the laser head.  This visual looks like the 
exhaust from a fighter jet when the afterburners are on - pockets of blue flame 
spaced about 1 foot apart.  In the jet engine this is due to the resonance of 
the engine and in the laser due to the resonance of reflection, power supply 
frequency, etc.  Most hobbyists use an adjustable length beam delivery because 
it is easier and takes fewer mirrors.

2.  The beam delivery system is pressurized with clean moisture free air or 
other cutting/purge gas to keep splatter and fumes away from the cutting lens 
and any mirrors near the cutting lens.  You can cut with pure O2 as this helps 
to oxidize the material as you cut.  We used large nitrogen tanks for purge air 
as we were cutting 10-12 hours/day.  Shop air can also be used if it is 
oil-less and dry.  If no purge air is used deposits will build up on the lens.  
If you can see smoke or splatter and do not have a purge system the 
particulates will build up of the optical surfaces and degrade the output.

3.  CO2 lenses have fixed focal lengths based on the beam delivery head.  The 
beam delivery head has the output lens recessed back into it a bit with purge 
air passages around the lens.  The air exits like a air gun but with a larger 
opening to allow the beam to exit.  If you want to work with a longer focal 
length you need a lens specific to that focal length.  Many industrial laser 
manufacturers have replacements lenses for under $100.  We had several sets of 
lenses with different focal lengths.  Stay away from Edmund Scientific or 
similar companies because they charge an arm and a leg for scientific lenses.  
They are good lenses but not priced as consumables.  For your power level you 
should never have to replace a good high power $100 lens.

Each lens was tailored (and prescribed by the manufacturer) for different 
materials.  We ran mild steel, stainless and aluminum.  Two of the three could 
get by with the same lens.  Don't remember which two at the moment.  A long 
focal length provides a small beam waist for a greater distance and is less 
subject to distance variation between the output lens and material.  A shorter 
focal length was better for cutting steel as the bulk of the beam was able to 
disperse more completely into the material from what I remember.  The long 
focal length has its advantages but once you pierce through the material the 
narrow beam keeps going into the support grating in the machine's bed (for a 
1/2" or so).

4.  All of our mirrors were mounted on machined aluminum blocks and water 
cooled.  Controlling the temperature of the mirrors helps to stabilize thermal 
expansion and unwanted beam steering.  As I remember the first surface mirrors 
were 99.5% or 99.75% reflective.  A mirror that absorbed 0.25% of the beam's 
energy at 4kW resulted in 10W of dissipation.  Not a lot of power but 10W 
builds up if not dissipated.  A smaller system would only dissipate 0.5W at 
0.5% loss & a 100W tube.

5.  Our system had a capacitive head to maintain a constant distance from the 
lens to the material.  Some of the hot rolled we cut was not the flattest 
material in the world.  If not cutting large pieces this is not as important.  
Capacitive sensing heads only work when cutting metals.  If trying to cut wood 
or plastic with a capacitive head, the head would keep moving down until it 
crashes into the material.  From the DIY standpoint you can use laser 
triangulation with a linear position sensing device, PSD, or a distance sensor 
like the Vishay VCNL4000 
(http://www.newark.com/jsp/search/productdetail.jsp?SKU=37T8990&&CMP=AFC-SF-T11).
  The VCNL4000 has an I2C interface and sensing distance of 1mm to 200mm.  It 
is most sensitive to distances in the 1-5mm range and has a non-linear output.

I have thought about rolling my own high power C02 system but just never had 
the time.  I would use multiple tubes at right angles from one another for 
higher power and scalability.  Start with one tube and add later.  The tubes 
would use pyrex or similar tubing with machined end caps to support beam 
delivery and laser gas cycling with a vacuum pump.  Direct electrode tubes like 
the one on ebay have

Re: [Emc-users] 3D printer ( high end )

[ceenbot]

For that matter the build chamber could be sealed off and flooded with shield 
gas to reduce waste.  You would have the issue of getting rid of the heat but 
coolant lines and a chiller work pretty well.  There is another company in the 
building I work in and they have a thin film vacuum deposition system.  They 
have mastered the art of vacuum deposited materials at low temperatures.  I 
have seen samples of silver coated surgical tubing, metal coated paper, etc.  
The surgical tubing increases in resistance as it stretches.  The vacuum 
chamber is cooled by a couple of Mitsubishi outdoor AC units.  


Dennis

>  
>  It would be interesting to see what could be done with a mig welder
>  using fine wire.  You would have to play with the current and speed to
>  get the deposition just right.
>  
>  Might get a little expensive in electricity, wire and gas.  And you
>  would need a welder that could handle a 100% duty cycle at the current
>  desired.
>  
>  Also, might have to stop every pass or two and let it all cool off.
>  
>  Dave

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Re: [Emc-users] Commutating Reactor

[ceenbot]

Did John run it for an hour or longer to be able to repeat the "only one hour 
run time situation"?  I forgot what the capacity of the borrowed generator was 
to compare it to a 15HP weak leg system.  Even if the generator varied in speed 
and voltage when loaded, one thing should be fairly certain - the phases should 
be 120 degrees apart.  That is helpful by itself.


Dennis


>  He ran it on a Diesel generator, and it did NOT trip.  So, it is
>  SOMTHING about
>  the power source.
>  
>  Jon
>

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Re: [Emc-users] Commutating Reactor

[ceenbot]

Hi John,

Too bad you can't connect your machine to a solid 3-ph line to see if the same 
issue happens regardless of the power source.  I had a handful of issues with 
my '86 VMC like loose PC boards, oxidized connectors, etc.  Now that it gets 
more use it seems to be doing better.  Keeping the caps charged makes it happy 
I guess.  Last year I fired it up after months of non-use and it worked fine on 
a Saturday but the Z-axis encoder went bad the next day.  Turns out I upset a 
mother mouse with my Saturday machining and she chewed through the nice 
Heidenhain shielded encoder cable!!  It was a 20 ft extension cable so I was 
able to shorten it a bit and get running again.  Now there are sticky traps in 
the machine's wire trays.  The kids drop dog food in the garage and the mice 
are quick about stuffing kibbles in my equipment.

A change in sound may indicate other issues like stressed driver silicon.  This 
may be electrical or thermal stress from its previous owner.  Even a tangential 
lightning hit may show up in weird ways.  Maybe an IGBT or MOSFET is on the 
edge of going and when it draws too much current the 611 trips out.


Dennis



>  >
>  > On 6/4/2012 6:40 AM, John Thornton wrote:
>  >> Yesterday I made some parts and had a giant fan on the drive to see if
>  >> it is a cooling problem. After about an hour or so the drive tripped
>  >> out. I forgot to mention that the only thing moving during these faults
>  >> is the Z axis and it is moving up ie the most loaded direction. Of
>  >> course I can make it trip out with S6000 M3 so it does point to the
>  >> infeed unit. I checked the internal cooling fan on the drives and they
>  >> all are running. After the fault I reset the drive and continued to
>  >> finish the last 5 parts without a fault. When it is about to fault out
>  >> on a rapid Z up move I can hear a change in the tone of the Z servo and
>  >> it starts to grunt for lack of a better word to describe the sound.
>  >>
>  >> The 600vdc buss is well protected as well as all the parts of the drive
>  >> system. By the time I could get it open on the bench any hot part would
>  >> be cool.
>  >>
>  >> I'll check the AC ripple today when I make some parts.
>  >>
>  >> John

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Re: [Emc-users] Encoder discs

[ceenbot]

I am making a batch of 1" diameter PC board wheels for use with the 75LPI
Avago AEDR-8300-1K1 quadrature encoder module.  The module is a reflective
style and the PC boards are gold plated for reflective purposes.  Plating
with gold makes for a very flat surface as opposed to HASL hot air leveled
solder which leaves bumps of solder and may not reflect straight back to
the sensor.


It's nice to hear that laser printed wheels cannot be "seen" with this type
of sensor.  I'm going under the assumption that the fiberglass between the
gold traces is not reflective enough to mess with the sensor.   Gerber
files are available for 75LPI and 36LPI parts if anyone wants a copy.  I
created the geometry once then copied it radially times 100 or 50
positions.  Goes prett fast.  A pic of the board is at: [LINK:
http://flic.kr/p/c9Y7Jo] http://flic.kr/p/c9Y7Jo


The same principle will work for bigger wheels.  The 75LPI wheel comes out
to 6.67mil wide traces and spaces.


I'm working with DC motors in the 32mm diameter range.  The DC motor has a
72MHz ARM Cortex-M3 on the back of it, motor driver and encoder.  Overkill?
 Maybe, but in the end we'll have a PID controlled motor, USB port,
programmable current limit for torque control and also scalable in the
future for 3-phase brushless DC.


Dennis


  > ---Original Message---
  > From: andy pugh
  > To: Enhanced Machine Controller (EMC)
  > Subject: Re: [Emc-users] Encoder discs
  > Sent: Jun 02 '12 10:15
  >
  > On 2 June 2012 15:21, cogoman wrote:
  > >   While I can see the need (sometimes) for a durable metal encoder
  > > disc, and I have cut some out of .016" copper (was on hand, and never
  > > got tested), I wonder how useful, or how durable laser printed
  > > transparency film would be for many applications.
  >
  > It works perfectly, with transmissive encoders.
  >
  > I had two problems: reflective sensors and a mandatory 75lpi pitch.
  > I tried laser-printing but I couldn't find a laser with a fine enough
  > dot-pitch to not alias at 75lpi, and the sensor was equally blind to
  > white and black. It needs shiny.
  >
  > --
  > atp
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Re: [Emc-users] Commutating Reactor

[ceenbot]

Hi Dave,

I have not found that the rotary phase converter slows in RPM during high low 
demands as it is still an asynchronous AC motor and is there is no torque 
demand on the motor shaft.  I don't think a flywheel would help here.  If it 
were physically connected to a 3-ph generator it would be another story and the 
15HP motor would look more like a 10HP from a shaft stand point when run from 
single phase.

A larger rotary phase converter would help though.  Sounds like your machine is 
sensitive enough that a 25-40HP rotary phase motor may be be necessary to get 
the impedance closer to that of the grid.  Adding more 3-phase motors to the 
system lowers the impedance of the WYE and helps to stabilize the wild leg as 
demonstrated with the lathe motor.  I'm entertaining the thought of adding a 
15HP motor to mine if I find a cheap one.


Dennis


>  ---Original Message---
>  From: Dave 
>  To: emc-users@lists.sourceforge.net
>  Subject: Re: [Emc-users] Commutating Reactor
>  Sent: May 31 '12 09:43
>  
>  You are probably right. When the drive load surges it is likely faulting
>  out on what it thinks is a lost phase or phase undervoltage.
>  
>  It might be interesting is to run this test again and put a clamp on
>  ammeter on each leg feeding your Mill and see how balanced the currents
>  are.
>  
>  I have never really had any problem with my phase converter running
>  loads so I haven't paid much attention to it, but I think I only have
>  run capacitors connected between one phase and the made up phase.   I
>  know I don't have any
>  between both of the two original phases.   I was always more concerned
>  about the current balance between phases than voltages.   The voltages
>  have always been  within reason ( as I recall ).   But then this is one
>  of those things that I don't pay much attention to unless it isn't working.
>  
>  I suspect that the 611 is expecting a stiff power supply - which most 3
>  phase services can provide.  If you have a large pulley you can attach
>  to your phase converter motor shaft to add inertia to the rotor, you
>  might want to attach it.  It would help the motor supply surge current
>  to the 611 drive.
>  
>  Dave
>  
>  

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Re: [Emc-users] Commutating Reactor

[ceenbot]

I also replaced my 15HP TEFC bearings with a pair from ebay.  Been quiet ever 
since.  The fan-end bearing was frozen and the balls were gliding on a grease 
film against the inner race.  It was noisy so I finally swapped them out.


Dennis


>  ---Original Message---
>  From: John Thornton 
>  To: Enhanced Machine Controller (EMC) 
>  Subject: Re: [Emc-users] Commutating Reactor
>  Sent: May 31 '12 07:51
>  
>  I'm sure fresh bearings would help the 15hp and it is a heavy duty TEFC
>  motor. I might pull it apart today and order some new ones...

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Re: [Emc-users] Commutating Reactor

[ceenbot]

Hi John,

   Sorry for the delay - just got back from a meeting. I also updated my
  email address so I can post again!! My ISP moved to Google services and
my
  email address changed. The EMC list had blocked posts sent from my new
  address.

I'm guessing your 2.5" facing mill may not be rated at 7.5kW average with
peaks of
  15kW during acceleration and deceleration. Does your facing mill have
  electronic drive controls or is it a plain 3-phase motor with belt
  reduction? I'm guessing our 7.5kW spindle drivers were built with the
  assumption there is a sturdy 3-phase supply to lean on.

   I posted a picture at: [LINK: http://flic.kr/p/c8pc7Y]
http://flic.kr/p/c8pc7Y showing the circuit mod. I
  forget the exact resistor and capacitor values but I just experimented
with
  a 5k and 220uF pair with a 10V bench power supply. To reach 90% of full
  value (9.0V) it took 5 seconds. Using a 1k resistor with a 220uF will
reach
  90% of terminal value in 1 second. My selection gave me about a 2 second
  time constant. Just now I emulated the Heidenhain 0-10Vdc control with a
  bench power supply. Connecting the resistor to the cap to limit the rate
of
  voltage rise on the capacitor and watching the cap voltage reach 9V took
5
  seconds with the 5k resistor. I remember inserting a resistor first and
  making sure the stepped speed program still achieved the RPMs I wanted it
  to. If you program it for 2000RPM and it only hits 1500RPM then choose a
  small resistor value. Somewhere in the 100 ohm to 4.7k ohm should work.
If
  the resistor is too high a value compared to the input impedance of the
  spindle driver you will simply have a drop in voltage at the spindle
driver
  and never achieve the speed you want. So, start with 1k without the
  capacitor and see if that changes your spindle RPMs. If ok then add (1)
or
  (2) 220uF capacitors to suit. This will add 1 to 2 seconds of delay to
slow
  the acceleration and deceleration of the spindle.

   If your spindle driver is analog like mine you may have a good chance of
  modifying your machine too. Old analog is great. No digital protocols or
  acknowledge packets to mess with. If you have schematics to the CNC
  controller, look for the spindle interface lines. If there is just one or
  two shown, you can break the connection and manually control the spindle
  speed with an external bench supply, potentiometer, etc.

   My experience was pretty straight forward looking back on it. It was the
  first rotary phase converter I built. When accelerating OR decelerating
  quickly, the spindle power meter would max out at 180% (meter would peg).
  This is normal for this machine. Accelerating would decrease the CNC's
  voltages and decelerating and dumping the spindle's brake energy into the
  rotary phase converter "grid" would increase the CNC's system voltages.
It
  was apparent to me that is was starving for power while quickly
  accelerating and I did not have a strong enough grid (rotary phase
  converter) to brake against. If the engine is too big for a car and
starved
  for gas or if the tires break loose while downshifting then don't
  accelerate as fast or decelerate as fast. The RC delay fixed it.

   Let me know what you find in your schematics.


   Dennis


   >Hi Dennis,

   >I have a 2.5" diameter facing mill that I use and I don't notice any
   >difference when using that. My machine lights do not dim during
   >acceleration which I assume is a good thing. I'm in the same canoe as
   >you with 240v single phase my only option to work with.
   >
   >Before all the experiments I could get 0 to 2k with no problems and
   >would structure my programs around that or use the G4 pause and ramp up
   >to the rpm I wanted above 2k.
   >
   >I too modified my program using a pause between S values but only had
to
   >do that going up in rpm. From 6k to 0 I've never had a fault.
   >
   >The resistor/capacitor would be a low cost experiment. How do you
   >calculate what the values are for the resistor and the cap? Did you put
   >the resistor in series with one of the control lines? Does the cap
   >connect to the upstream side or the downstream side of the resistor?
   >Maybe a stick drawing would help me understand...
   >
   >John
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